Transparent reenforced waterproof sheet material



Oct. 9, 1934. E, M KRATZ T 1,976,028

TRANSPARENT REENFORCED WATERPROOF SHEET MATERIAL Filed May 16. 1950 VE 2D Patented Oct. 9, 1934 UNITED STATES TRANSPARENT REENFORCED WATER- PROOF SHEET MATERIAL Edouard M. Kratz, Chicago, Ill., assignor, by

mesne assignments, to Marsene Products Co., a

corporation of Illinois Application May 16, 1930, Serial No. 452,905

7 Claims.

This invention relates to the manufacture of strong, exible, waterproof, grease-proof, transparent sheet material having great utility as a. wrapping or covering for articles of all kinds.

Transparent, gelatine sheet material has long been in use as a wrapping for various articles, such as food stuffs, candies and the like. This materlalis, however, quite hygroscopic and takes up moisture from the air in damp weather, becoming quite soft and flabby. On the other hand, under dry atmospheric conditions this material loses moisture to the air, thereby becoming very brittle. Further, because of this property it is not possibley to keep wrapped articles in their original condition during changes in humidity, as when the humidity is high moisture will pass through the wrapper to the article and vice versa. Articles desired to be maintained in a moist fresh condition, therefore, will on dry, warm days lose their moisture through the sheet to the air, thus becoming dry and stale.

By combining gelatine with a sulphonated oil,

as in my. application No. 10,962, filed February 21, 1925, a better sheet material is obtained than when using only gelatine, but this product is also to a certain extent open to the above objection.

Gelatine and gelatine composition sheets moreover possess the disadvantage in that they tear easily when once ruptured. This is .largely due tothe fact that these materials have no brous base as has paper and the like and must rely entirely on the cohesion of its molecules to withstand tearing and similar stresses. Because of this feature, gelatine and gelatine composition rwraps are often not durable enough to withstand the rough usage and handling that they must undergo in practice.

I have now devised a sheet material which is not only fiexible, Waterproof and greaseproof, but also strong enough to withstand any tearing or rupturing stresses imposed on the material in use. Y

It is accordingly 'an object of my invention to provide a transparent, durable, waterproof sheet material strongly resistant to tearing stresses and the like.

A further object of this invention is to provide a tough transparent sheet material which, when used as a wrapping orthe like, will maintain the wrapped articles in their original condition and will effectively withstand any deteriorating stresses that a wrapping or the like is :t subjected to.

Other and further important objects of this invention will become apparent from the follow- :lng description and appended claims.

Referring now to the drawing which discloses a preferred form of sheet material:

Figure 1 is a top plan view of such sheet ma-` terial.

Figure 2 is a longitudinal sectional view through the sheet material of Figure l on an enlarged scale.

The sheet material of this invention, indicated generally by the reference numeral 1, comprises a base 2 of gelatine, or gelatine composition, preferably a gelatine sulphonated castor oil composition. Such a composition, for instance, is disclosed in my copending application Serial No. 10,962, filed February 21, 1925, and is composed of from about 40 to 85% of gelatine and 15 to of sulphonated oil. The base 2 is reenforced' and its tensile strength materially increased by incorporating therein a fibrous body 3 as disclosed in my copending application Serial No. 432,981, filed March 3, 1930. Said fibrous body 3 may comprise a great variety of fibrous materials such as cotton goods, cotton netting, cheese cloth, tarlatan, crinoline, silk noils or the like. Preferably, however, as shown, the body 3 is in the form of a netting or skein in which the area of the open spaces 4 greatly exceeds the area of the threads 5. Further, said fibers Aor threads 5 are interwoven so that the openings 4 are even and regular in order to produce a sheet of uniform strength throughout.

The fibers 5 of the body 3 are also usually starched or sized to prevent distortion of said fibers and to aid in aligning the body on the base 2 and improve the transparency of the finished sheet.

Said fibrous body 3 may be incorporated in the base 2 according to the process of my copending application Serial No. 432,981, filed March 3, 1930, by employing the apparatus disclosed in my Patent No. 1,650,585. This process broadly cornprises applying the fibrous body 3 to the traveling belt of said apparatus before that part of the belt to which the body is applied passes the gelatine coating rolls. In moving between the coating rolls the belt with the fibrous body thereon is coated with a film of a fluid gelatine solution or composition. As the belt with the coated fibrous body passes over the horizontal or nearly horizontal surfaces of a chill box, the gelatine solution passes through the interstices of said fibrous body and sets to form the base 2, leaving the body in relief on one side of the base as shown in Figure 2. The exposed surfaces 6 of the individual fibers 5 will, however, be coated with the gelatine of the base and the fibrous body firmly anchored in said base.

The reenforced sheet so formed while it possesses a high tensile strength is not waterproof and, as explained above, will in humid climates take up moisture, thereby becoming soft and flabby. The fibrous body 3 will not, moreover, aid the sheet in this respect for upon the thin coating of gelatine on the exposed surfaces 6 of the fibrous body becoming moist, the fibers 5 of said body will transmit the moisture to the base 2, thereby causing the base to swell and decreasing the adhesion between the base 2 and said body 3.

The reenforced sheet is accordingly rendered waterproof by applying to the surfaces thereof the waterproof coatings 8 and 9.

A highly desirable coating for this purpose is disclosed in my copending application Serial No. 450,063, filed May 5, 1930 and suitably consists of 40 to 75% of cellulose nitrate, 25 to 60% of a natural or artificial gum, preferably dammar, 0 to 5% of a Wax or petrolatum, and 0 to 40% of a plasticizer such as tri-cresyl phosphate or dibutyl phthalate. The dammar gum in this coating composition provides the function of anchoring the coatings firmly to the gelatine base 2 and is especially necessary in the coating 8 which covers the smooth surface of said base. The plasticizer, of course, is for the purpose of rendering the coating flexible.

The coating 9 applied to the surface of the base 2 havingthe fibrous body 3 thereon as seen in Figure 2 passes through the interstices of said body 3 to thereby become anchored to the base.

Said coating also spreads over and completely encloses the exposed portion of the fibers 6 of said body 3 and becomes very firmly anchored thereto. It will be appreciated, of course, that the anchorage of the coating 9 to the fibers 6 of the body 3 is materially greater than to the base 2 and therefore said fibrous body 3 performs the additional function of increasing the degree of adhesion of the waterproof coating 9 to the base 2. Furthermore, the spreading of the coating composition around the exposed portion 6 of the fibers 5 renders the fibers highly water repellent and prevents their transmitting moisture to the base 2.

A reenforced base 2 may be provided with said coatings 8 and 9 by dissolving the above mentioned coating composition in a mixture of solvents comprising ethyl acetate, anhydrous ethyl alcohol, toluene and butyl acetate to form a rapid drying solution. This solution, which is in a fairly fluid state, is then applied to the reenforced base while the same is in a suspended state, the excess of solution being removed by means of doctors and the coatings dried by passing the base through a hot air drier. The water-proof coatings 8 and 9 thus formed are continuous films of extreme thinness, in the neighborhood 'of 0.00015 inch.

The resulting sheet material, as will be apparent, is highly water repellent, flexible and has a high tensile strength and is therefore adapted for a great variety of commercial uses, as for wrappings, bags, covers and the like. Moreover, this material may be modified in different ways to suit any particular use for which it is desired. For example, if it is desired to use the material for a garment bag, a small amount, say about 0.5 to 1% of a conventional moth repeller such as camphor, naphthalene or the like will be included in the cellulose ester coating. Furthermore, when used for this purpose the wax or petrolatum constituent of the coating will be eliminated, as otherwise grease stains might form on the garments in the bag.

On the other hand, if the material is to be used to-wrap ices, candies, and frozen products, the wax content will be relatively high in order to prevent freezing of the wrapper and the adhesion of the wrapped products to the wrappers.

If a highly attractive colored sheet is desired for any purpose, the required colors can be imparted to the sheet by incorporating a dye, pigment or the like in the gelatine or gelatine sulphonated oil base. Of course, the desired colors could be given to the sheet by employing a colored reenforcing fabric, but as this would necessitate a stock of fabrics of many different colors, it is found more efcient and practical to color the gelatine base and employ an uncolored reenforcing fibrous body. The fibrous body will then absorb sufcient color from the gelatine or gelatine sulphonated oil base to become dyed itself f It will thus be appreciated that I have disclosed a very strong, Waterproof, attractive sheet material of a transparent nature which will find great utility in the wrapping industry and related art. Furthermore, the fibrous material employed in the sheet not only increases the tensile strength of the same but also aids in anchoring a waterproof coating to the base of the sheet.

I am aware that various details of my invention may be varied Without departing from the spirit of this invention, and accordingly I do not intend to limit the patent granted thereon except as necessitated by the prior art.

I claim as my invention:

1. Strong, transparent, Waterproof sheet material comprising a thin gelatine base, a reticular fabric body incorporated in said base so as to lie in relief on one side thereof, with portions of the base exposed therethrough and a continuous coating of cellulose ester firmly anchored to the parts of said fabric in relief and the exposed surfaces of said base.

2. Strong, transparent sheet material comprising a thin, gelatine base, a netting of cotton fabric in said base so as to lie in relief on one face thereof with parts of the base exposed therethrough and a coating of cellulose nitrate containing dammar gum firmly anchored to the parts of said netting in relief and the exposed parts of said base.

3. Strong, transparent sheet material comprising a colored, gelatine-sulphonated oil base, a netting of cotton fabric in said base so as to lie in relief on one surface thereof, a coating of cellulose nitrate containing dammar gum firmly anchored to the parts of said netting in relief and the exposed parts of said base and a similar coating anchored to the other face of said base.

4. Strong, transparent sheet material comprising a thin gelatine base, a fabric netting in said base and lying in relief on one surface thereof, a coating of cellulose nitrate containing an anchoring agent and a moth repeller firmly anchored to the parts of said netting in relief and the exposed parts of said base.

5. Strong, flexible, transparent, Waterproof sheet material comprising a gelatinous base, reticular fabric incorporated in said base so as to lie in relief on one side thereof, the remaining side of said base being fiat and substantially unaffected by said reticular fabric, and a film of a cellulose ester on each side of said sheet material.

6. Strong, transparent sheet material comprising a thin base film of protein material, a fabric netting embedded in said base film and lying in relief on one surface thereof and a coating of cellulose ester firmly anchored to said base film.

7. Strong, transparent sheet material comprising a thin base film of protein material, a fabric netting in said base and lying in relief on one surface thereof, and a coating of a cellulose ester -firmly anchored to the parts of said fabric in relief and to the exposed surfaces of said base film.

' EDOUARD M. KRATZ. 

